Major depressive disorder (MDD) is characterized by a dysregulated fronto-limbic network. The hyperactivation of limbic regions leads to increased attention and processing of emotional information, with a bias toward negative stimuli. Pathological ruminative behavior is a common symptom of depressive disorder whereby the individual is unable to disengage from internal mental processing of emotionally salient events. In fact, lower deactivations of the neural baseline resting state may account for the increased internal self-focus. The insular cortex, with its extensive connections to fronto-limbic and association areas has recently also been implicated to be a part of this network. Given its wide-reaching connectivity, it has been putatively implicated as an integration center of autonomic, visceromotor, emotional, and interoceptive information. The following paper will review recent imaging findings of altered insular function and connectivity in depressive pathology.

The current study investigated the immediate neurophysiological effects of different types of massage in healthy adults using functional magnetic resonance imaging (fMRI). Much attention has been given to the default mode network, a set of brain regions showing greater activity in the resting state. These regions (i.e. insula, posterior and anterior cingulate, inferior parietal and medial prefrontal cortices) have been postulated to be involved in the neural correlates of consciousness, specifically in arousal and awareness. We posit that massage would modulate these same regions given the benefits and pleasant affective properties of touch. To this end, healthy participants were randomly assigned to one of four conditions: 1. Swedish massage, 2. reflexology, 3. massage with an object or 4. a resting control condition. The right foot was massaged while each participant performed a cognitive association task in the scanner. We found that the Swedish massage treatment activated the subgenual anterior and retrosplenial/posterior cingulate cortices. This increased blood oxygen level dependent (BOLD) signal was maintained only in the former brain region during performance of the cognitive task. Interestingly, the reflexology massage condition selectively affected the retrosplenial/posterior cingulate in the resting state, whereas massage with the object augmented the BOLD response in this region during the cognitive task performance. These findings should have implications for better understanding how alternative treatments might affect resting state neural activity and could ultimately be important for devising new targets in the management of mood disorders.Electronic supplementary materialThe online version of this article (doi:10.1007/s11682-011-9146-z) contains supplementary material, which is available to authorized users.

Massage therapy has been reported to reduce state anxiety, stress hormonal levels and depressive symptoms in diverse populations. However, the neural mechanisms by which massage might impart therapeutic-like effects have yet to be determined. In the present neuroimaging study, we investigated the impact of different forms of tactile stimulation on neural activity in healthy participants. In this regard, Swedish massage and reflexology were associated with substantially less neuronal activation during the course of the scanner session. These data suggest that tactile stimulation, as provided by different types of massage, may dampen the normal levels of activation in several brain regions important for mood and arousal (e.g. cingulate gyrus, parahippocampal gyrus). Further investigation is ultimately required to understand the long-term mechanisms by which touch operates at a neural level and how massage therapy might have a beneficial role as an adjunct treatment for mood disorders in clinical populations.

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